Objective: Diets of lower energy density are associated with higher diet quality, lower body weights, and better health outcomes. This study examined associations among dietary energy density, energy-adjusted diet costs, and socioeconomic indicators of study participants.
Design: In this cross-sectional study, energy and nutrient intakes for 164 men and women aged 25 to 65 years were obtained using a food frequency instrument between June 2005 and September 2006. Dietary energy density (kcal/g) was calculated with and without beverages. Energy-adjusted diet costs ($/2,000 kcal) were calculated using food prices in Seattle, WA. Tertile splits of energy density and energy cost were analyzed using tests for linear trend. Linear regression models tested the association between education, income, and dietary variables, adjusting for age and sex.
Results: Diets of lower energy density were associated with higher absolute nutrient intakes. Diets of lower energy density were also associated with higher energy-adjusted diet costs. Conversely, highest energy density diets were associated with lower intakes of micronutrients and fiber and lower costs. Education and household income showed a negative association with dietary energy density in regression models. Education and household incomes showed a positive association with the energy-adjusted cost of the diet. Education was a stronger predictor of both energy density and energy cost than was household income.
Conclusions: Higher-quality diets were not only more costly per kilocalorie but were also consumed by persons of higher educational level. The influence of diet quality on health, observed in some epidemiologic studies, might be modulated by unobserved indexes of socioeconomic status.